Rapid COVID immune status test launched in UK, Ireland

You've had your two COVID-19 jabs, but are you actually protected against infection? That's a question that a fingerprick test launched today in the UK and Ireland could help to answer.

The test – originally developed by US manufacturer Chembio Diagnostics – has been introduced into the UK and Irish markets by Guilford-based Luas Diagnostics and tests for the presence of SARS-CoV-2-targeting antibodies in the blood.

While there are plenty of tests already available that can give a yes/no reading of whether antibodies are present, the Chembio test measures the level of antibodies as well, so can tell whether a patient is likely to be protected against the coronavirus.

The test can detect, differentiate and quantify IgM and IgG receptor binding domain antibodies to SARS-CoV-2 in 15 minutes using a portable reader device, according to Luas. Antibodies should be present in people who have previously exposed to the virus, or been vaccinated against it.

Commenting on the approval, University of Oxford virologist William James said that the test could be valuable in deciding whether and when booster jabs may need to be administered.

"Being able to distinguish the IgM from the IgG class of antibody response will also provide potentially useful information about the stage of a person's immune response, and its likely persistence over time," he added.

IgM antibodies are produced as a body's first response to a new infection, while IgG antibodies form the bulk of the immune response, and are the type that reactivates quickly if a vaccinated person is exposed to a pathogen for the first time, or in the case of re-infection.

"A recent study has shown that 10-15% of people, particularly among the higher age group, may not produce antibodies even after the second dose of vaccine and thus may have limited protection against the virus," said Brendan Farrell, chief executive of Luas.

The diagnostic was awarded a CE Mark in the EU in January, paving the way for its rollout in Europe, although in the US Chembio's request for an emergency use authorisation review of the kit was turned down by the FDA.

The US regulator has been scaling back the use of the EUA regulatory pathway, and according to Chembio declined to review the test as it would have "relatively limited impact on testing accessibility or testing capacity" in the US.

Other companies have also been developing quantitative antibody tests for COVID-19, including Abbott which claimed a CE Mark for its IgG measuring test last December and has also filed an EUA request with the FDA.

Another player is FlowMetric Life Sciences, which launched its quantitative diagnostic – VaxEffect – in the US two weeks ago.